I understand that wiring inside of junction boxes must be accessible.
Are boxes that were under the floor prior to a certain date "grandfathered?" (I'm talking twist, solder, and tape splices from K&T.)
In an attic, for example, can one mount a JB such that with a cover it would be flush with the floor? If it's OK by code, I don't think the usual metal covers (silver colored with the teardrop-type screw hole on one side) would be a good choice here because dust/dirt/etc. can enter. Is there such a thing as a plain plate made for a JB? I have seen 5", white, metal plates but nothing in 4".